A Grandfather's Mistake
by Wannabe-Fantasy
Summary: Sierra Carlston is a Slytherin, shunned because of her friendship with the Golden Trio and co. She belongs to a new type of Pureblood Slytherin, those who have decided to take matters into their own hands. A package delivered for her from Lord Voldemort himself, changes her life and forces her to confront her hidden feelings and make choices that could tear her family apart.
1. Background Information

**Disclaimer: I do not own Harry Potter and am not affiliated with the series in any way. The Carlston family are a figment of my imagination. Any similarities between them and any other 'official' characters or OC's is purely accidental.**

**The title is subject to change, so if you do like the story please put it on alert! Or take note of my penname to check for updates!**

**Hello everyone! This is my new story, involving my OC Sierra Carlston. This is some background info that I feel is necessary to read to understand my story better. Thank you!**

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**I would like to say now that I have changed the timeline of the story we all know and the characters who have died/lived. **At this time, the Golden Trio are 18, they have just finished Hogwarts- the story takes place beginning in the summer after their 7th year. Dumbledore was killed in their 7th year. Sirius did not die in their fifth year, but the HQ of the Order of the Phoenix was discovered and was subsequently moved to an old property of the Potters, to whom the Carlston family is related. Sierra is a distant cousin of Harry's.

Sierra Carlston is 18 years old, with long, curly blonde hair which is usually quite big and grey eyes. She is a pureblood Slytherin and has been best friends with Blaise Zabini since childhood and very close friends with Draco Malfoy and Lisa Kerrings (another OC and Ravenclaw) from a young age.

The Carlston family have always been quite involved in the Dark Arts, with her grandfather Tobias and her great uncles being amongst the first official Death Eaters. Her father and his brothers were also Death Eaters and attended Hogwarts at the same time as the Mauraders. However the younger generation of Carlstons have started to break away from the strict following of the Dark Arts.

Sierra has four brothers, three of whom are older. James is the oldest Carlston sibling, with twins Liam and Lucas coming after him. Sierra's younger brother Alexander is the first Carlston in generations not to be in Slytherin, but took after their mother and was Sorted into Ravenclaw. I imagine her oldest brother James to be around 24 and the twins a year older than Fred and George, so around 21/22.

Sierra was in the same year at school as Harry, Ron and Hermione. During their 6th year, Sierra befriended them whilst helping them in their fight against Voldemort. For doing so, Sierra was told not to return to the family home by their parents and was taken in by Molly Weasley. She is quite close with her brothers, but all were unable to take her in as James lives at home working with their father and the twins work in Romania with Charlie, although they are younger. Alexander is only in his 4th year at Hogwarts.

During her stay at the Weasley's, she became close with Charlie, Fred and George who reminded her a little of her brothers. She became good friends with the twins especially and came to see the Weasley's as family. Upon leaving Hogwarts, she officially joined the Order of the Phoenix and witnessed the death of her parents in a fight between members of the Order and Death Eaters. Her brother James became head of her immediate family and her mother's sister Antonia, who disapproved of her sister's involvment in the Death Eaters and Dark Arts, moved in to help run the household. Sierra returned home but remained very close with the Weasley's and spent a lot of time at the Order's HQ, where Remus, Hermione, Harry and Sirius lived permanently.

Sierra belongs to a group of Slytherins who have grown tired of the war. They don't share the views of their parents and grandparents and would rather live in an equal society. Blaise Zabini, Astoria Greengrass, Malcolm Baddock, Miles Bletchley, Tracey Davis and Draco Malfoy- who sought sanctuary with the Order after failing to kill Dumbledore- are all members amongst others. They work within the Death Eaters and Slytherin House secretly. Their methods are more ruthless than that of the Order and they view anything less than 100% loyalty to their cause as a betrayal.

A few days ago, Sierra recieved a package from Lord Voldemort himself. Upon opening it, she discovered family secrets that would change her life. This is where Sierra's story begins...

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**Well? I hope this wasn't too much to take in and please, feel free to ask me any questions you have. Slytherin names were taken from the Slytherin page on the Harry Potter wiki site. I hope you enjoy the story and reviews and constructive criticism are always welcome. Thank you! **


	2. The Revelation

**This is the first official chapter of my new story! I hope you enjoy it and if you have any questions, _please just ask_! I understand that jumping right into the story may seem confusing but I've included a small back story in the previous chapter. I have also kept some characters alive and changed a few details.**

**Disclaimer: I do not own Harry Potter and am not affiliated with the series in any way. Sierra Carlston is my own character.**

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"The bottom line is, you either have to get married to a reputable bloodline Sierra, or you'll end up in service for Voldemort. And that could be anything from joining the Death Eaters to being one of his experiments."

Sierra Carlston stared up at Remus Lupin in a daze, her grey eyes wide, trying to comprehend what her old professor, and now friend was telling her. He was staring back at her hardly, willing her to understand and keep somewhat calm.

The gloomy room that they were currently holed up in was silent. Sierra and Remus had gathered the Weasley brothers and Molly, Hermione, Harry, Sirius and Kingsley Shacklebolt to discuss the curious contract that had been delivered to Sierra some days previous. The rest of the Order of the Phoenix were currently downstairs in Headquarters, an old property which had once belonged to the Potter family, planning a raid on an abandoned house which looked as though it was being used by Death Eaters as a base.

Sierra shook her head slowly, her frizzy blonde curls tickling her face. "I don't _understand!_ Why was this never mentioned to me? None of my cousins ever had this! Or my brothers! How could this happen? Married? To who? I don't-"

"_Sierra!" _Kingsley had stepped forward, his voice steady and reassuring, "Let Remus explain."

Remus straightened up and addressed the astonished room. Fred and George had moved to Sierra's side, each having a hand on one of her shoulders. He smiled inwardly when he saw the identical bewildered looks on Ron and Harry's face, an expression so familiar to him from trying to exlpain something to James and Sirius in their schooldays. The present Sirius however, was looking downright terrifying, a furious look etched upon his face. He was extremely fond of Sierra, having known her father well.

"Right," he cleared his throat, "From what I have been able to gather upon reading the contract and what research I have been able to carry out, it seems as though your grandfather ended up in debt to Lord Voldemort. You know the Carlston family has some sinister ties, your grandfather Tobias and great-uncles having been amongst the first Death Eaters- _I know you and your brothers are different Sierra_- but in doing so, they were tested to the edge.

It seems that at one point, your grandfather failed in a mission. He was to kill a Muggle family- a source of amusement really, for Voldemort- but he did not kill the young children, believing them to be no threat. Obviously, Voldemort was furious. Not at Tobias not killing the children, but at him disobeying orders. Voldemort was beginning his career, establidhing his reign of terror. Tobias was older than him, so he had to assert more dominance over him. If Tobias was seen to be let off with being disobedient, then perhaps others would not follow orders either, seeing Voldemort as lenient. So Voldemort, not entirely willing to kill one of his first, and up until now, most loyal followers, decided to make an agreement with him, using Tobias' weakness, as he saw it, against him.

Tobias was to give his first born daughter to Voldemort's service. At this time, it was not customary for women to be Death Eaters, and if they did join, they would not rise high in the ranks, Bellatrix being the exception. To give his daughter to Voldemort would surely mean his daughter being a... slave to the Death Eaters, or perhaps being used in an experiment of sorts."

Remus stopped here, letting the information sink in. Sierra was still, her hand clutching Hermione's as Molly stroked her hair gently, nudging George over. The Weasley's all looked both angry and slightly confused, they had not believed Voldemort would feel any sort of hesitation in killing anyone.

A smoldering anger was clearly consuming Sirius, who bitterly resented the hold Voldemort had over families, yet Harry looked unsurprised. Not much shocked him anymore. Remus sighed. It wasn't fair. Not on Harry, or Sierra. He himself had been horrified upon discovering the meaning of the contract, even more so upon realising that Voldemort had of course not forgotten the deal. Blaise Zabini however, Sierra's best friend since childhood, who had been assisting Remus with the research had been furious although entirely unsurprised. Apparently it had not been uncommon for old Pureblood families to exchange children for riches, or for leniency in lost feuds.

Remus continued, "Upon your father not having any daughters, he made a clause in the agreement with Tobias. His eldest son's first daughter was instead to be given. If Robert failed to produce a daughter, then Voldemort would conduct a massacre upon the Carlston family, believing that he was being deliberatley disobeyed. In fear of this, Tobias never told anyone of the contract. Only one of his brothers, Charlus, knew of it and he was sworn to secrecy. When Robert kept having sons, Tobias grew both concerned and relieved. Your family was strong and loyal to each other and as far as Tobias knew, to Voldemort, despite his temporary absence. He began to believe some of you would withstand Voldemort's wrath. Of course then, you were born. And Tobias knew that once you turned 18, if Voldemort returned- and Tobias had no doubt that he would, although he died before Voldemort's reappearance in your fourth year- you would have a limited amount of time to either marry into a pure bloodline, or you would be forced to join Voldemort.

Voldemort didn't forget. And he has decided to collect. So you now must marry before your 19th birthday, or join Voldemort, and risk a massacre if you don't."

There was a resounding silence before an explosion of noise. Sirius was bellowing along with the Weasley brothers, a jumble of swears and threats. Molly and Hermione whispering furiously to a stunned Sierra, who was unnaturally lost for words. Harry stood staring thoughtfully out the window, most likely, knowing him, trying to come up with a rescue mission.

"Quiet," Kingsley spoke steadily. He stood and his presence, as always, was so powerful that silence came over the room once more. He looked to Sierra. "Are you okay?"

Sierra looked up. She no longer looked stunned, but had allowed her years of Slytherin training to kick in and had resumed a calm and expressionless mask. "There is no way I can get out of this without destroying my family?"

"No."

"Are my brothers aware?"

"Blaise was conducting the research with me, so he's probably told them."

She nodded vaguely. She honestly didn't know what to do. Or say. Curling up in a ball and screaming and crying for a while seemed like a wonderful idea. She remembered her affectionate and generous grandfather who doted on her and felt a frighening tsunami of rage and betrayal consume her. But she was a Carlston and a Slytherin. She knew how to conceal her emotions and she knew how to keep an emotionless and professional air. She may have been amongst friends, but she wouldn't allow herself to be seen as weak.

Remus watched her closely. He too, had known Robert Carlston at school. He had been a few years older and a Slytherin, but he had never been cruel and as far as Remus had seen, he had never been fanatical, or really interested in blood purity as his fellow Slytherins had been. If it had not been for his brothers or family name, he most likely would have shunned. He could see Sierra was shaken, but knew that she would never admit it. She would tackle the issue and not run. He felt a warm pride within him, the young people that were now taking their turn to fight against Voldemort were certainly afraid of the fight.

Sierra spoke again, her voice steady although she clutched Hermione and Molly's hands. "What are my options?"

Remus nodded grimly at Kingsley, who answered her. "Not marrying before you turn 19 will mean you are to join You-Know-Who. If you refuse to do so, which I imagine you will, it will mean a brutal, and most probably, a futile fight against him."

Sierra breathed deeply. "And if I choose to marry?"

"We also looked into this. We assumed you'd rather marry a friend, but there is a cut-off member of Blaise's family who was a Squib. Draco is engaged to the youngest Greengrass. Everyone else we looked into either had a hidden family secret or was a little less Pureblood that they cared to admit. There were however two options."

"Well?!" Molly exclaimed, as Charlie wrapped a comforting arm around her shoulders. She was clearly rather upset. She thought of Sierra as family and couldn't help but feel distraught at the thought of the young girl being so backed into a corner. She knew Sierra's love for her family, her brothers especially and assumed she would rather enter a most likely loveless marriage than allow them to come to harm. And over her dead body would Sierra marry someone who was less than decent towards her.

Remus shifted, looking uncomfortable. Sirius, having guessed gave a small smile, hastily covering his mouth as Hermione glared at him, also knowing Remus' response.

"Well, come on Remus, I'd really quite like to know my options for who I'm going to have to possibly spend the rest of my life with!"

"Yes, of course. Well, we discovered that Theodore Nott is a viable option. He's Pureblood, no hidden away family members. His father is a Death Eater, and we're pretty sure he is as well. The other choice, considering that the main requirement is simply that he must be of a clean bloodline... the other choice is one of the Weasley boys."

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**Of course, the traditional cliff-hanger first chapter! I hope you enjoyed it and please remember to ask any questions you have and to review! I'll gladly take all suggestions and constructive criticism on board. Thank you for taking the time to read!**


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